# Questions tagged [wilcoxon-signed-rank]

a non-parametric rank test to compare two paired samples, whether values in one are bigger than in the other. This test is NOT the same as the sign test.

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### Basic question regarding before and after intervention analysis on groups of different sample size

Apologies for the basic nature of this question. I have collected data before and after an intervention and assessed response to the intervention using a survey. This was a basic survey using a 1-5 ...
1k views

### Use of Wilcoxon test for non-normal data akin to Two One Sided T-test

I'm analysing paired data for equivalency and it's not normally distributed, i.e., the difference of the paired result is not normally distributed due to, amongst other things, outliers. If it were ...
139 views

### What do these Wilcoxon values tell me?

I did a pre and post-test with a small number of students ($n=12$).These values came after a science intervention that took $4$ weeks. I used a Wilcoxon test for 2 related samples as there was not a ...
29 views

### Wilcoxon test on distribution derived from bootstrapping

We have two Chocolate bags X and Y. Each chocolate bags have total 1000000 chocolate boxes randomly sampled from 100 types of chocolate boxes (B1, B2, …, B100). These chocolate boxes are of different ...
42 views

### Paired t-test on dependent samples

I have a set of paired observations, corresponding to patient blood pressure before and after a treatment. I'd like to test for the significance of the treatment by conducting a paired t-test (or ...
181 views

### Does Wilcoxon Signed Rank (paired test) in R automatically analyse data by row?

I have multiple rows of observation periods [OP] (of varying durations) showing the average food intake rate of the first quarter of the OP compared to the last quarter of the OP. See the table below....
1 vote
424 views

### paired Wilcoxon rank test but with 3 groups

What is the statistical test I should use if I want to run a paired sample Wilcoxon’s signed rank test but I have three groups to compare instead of two?
73 views

### Kruskal-Wallis Test shows significance, but Pairwise Wilcoxon Rank Sum Test does not

I used the following code to perform a Kruskal-Wallis test on a dataset, which gave me a significant p-value (5.159e-06). However, when I then use pairwise.wilcox.test() to perform a Pairwise Wilcoxon ...
622 views

### Why is the upper bound of the 95% CI infinity when using a one sample wilcoxon?

I've been calculating 95% confidence intervals around the psuedomedian in a one sample wilcoxon signed rank tests, with a "greater" alternative and the mu = 0. That is, I have been exploring ...
10 views

### simulate the number of samples to be statistic relevant using a non-paremetric paired test

I have an experiment where a group of subjects must learn to associate some sounds to images (say, sound 1-image 1, sound2-image 2,... soundN-imageN). They do a memory test (we present sounds and ...
218 views

### Transitivity of Wilcoxon signed-rank test

I have performed Wilcoxon signed-rank tests for variables $X$, $Y$, and $Z$, where it appears that (speaking informally) $X < Y < Z$. Indeed, the p-value for the one-sided Wilcoxon signed-rank ...
2k views

### Appropriate tests on discrete and paired data

I am going back and forth on which tests to do. I have two paired variables, that are both positive integers (0,1,2,3...etc). $n = 559$. The variables represent the error resulting from two different ...
542 views

### How to run Friedman test correctly across three sets of questionnaire data divided into sub-groups?

I am trying to evaluate the usability of three prototypes of an application and want to see if there is a significant difference in terms of usability. For this I have collected responses from users ...
1 vote
377 views

### Metrics in comparing the rank orders of elements from 2 vectors

I am working on sampling a posterior distribution for parameters in my model using approximate Bayesian computation (ABC). I would like to come up with a summary statistic to compare the similarity/...
1k views

### Paired t-test with multiple observations per pair

I have a bunch of websites websiteA....websiteZ for example. Now I have an optimization technique that possibly improves the performance of these websites. I want to check whether this technique ...
334 views

### Calculating effect size of wilcoxon test after correction for multiple comparisons using R

I am trying to compare two amino acid concentrations after two treatment variations. The data is not normal distributed, so I have to use non-parametric tests. I calculated the adjusted p values, but ...
30 views

### Multiple testing with Wilcoxon signed rank test with set maximum length

I'm essentially performing this test with the Java Apache math3 method which only allows lengths up to 30. My pairs will have a length of maximum 2048. I will be testing for an increase (combination ...
476 views

### Statistical test to compare models results for concordance index

I'm working on a model for survival prediction and using the concordance index to evaluate the results (https://medium.com/analytics-vidhya/concordance-index-72298c11eac7) . I want to show that my ...
1 vote
10 views

### investigation of a potential change of measured values: only the simple linear regression or also compare the mean of follow-up values with baseline?

For my medical dissertation I am studying a group of 36 patients. The patients received a drug repeatedly over several months. Serum levels of two cytokines were measured in the patients both before ...
18k views

### Non-parametric test if two samples are drawn from the same distribution

I would like to test the hypothesis that two samples are drawn from the same population, without making any assumptions about the distributions of the samples or the population. How should I do this? ...
39 views

### Validity of Wilcoxon Signed Rank or Spearman for 2 Likert Scales

I am working on my MSc dissertation findings and I have data results from two 5-Point Likert scales. One Likert measured self-assessed behaviour, whilst the other measured attitude. (Both scales were ...
13 views

### Test(s) for comparing predictor quality for different features?

I applied a predictor to different numeric features from the same group of subjects (n>1000). The features have different ranges. Is it possible in this case to apply a statistical test to make a ...
662 views

### Questions about Wilcoxon signed rank test

I wanted to conduct a Wilxocon signed rank test but stumbeld upon two questions that I am unable to solve on my own. I tested 2 types of interfaces for a software with the same ten people. I want to ...
1 vote
326 views

### Pre-test post test single group design using likert scales

I've been asked to analyse some data and I'm struggling to get my head round it. 14 people in a therapy group were rated on a questionnaire containing 16 6-point Likert scale questions when they ...
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### Zero differences and Wilcoxon signed rank test

I am wondering if the Wilcoxon signed rank test is an appropriate test for my data, that does not follow a normal distribution. I have 150 datasheets of numbers of drugs measured at two points in time....
1 vote
48 views

### Constant p-value for all my tests

I am comparing the performance of two AI models across 15 data sets. One model performs heavily better than the other on all the performance metrics. When I perform a one-tailed Wilcoxon signed rank ...
57 views

### Two sample t-test vs One-sample t-test on residuals [closed]

For some arbitrary data, I have the raw data and a fitted model (not a regression model, but more so a model that accounts for noise and imperfections the data acquisition). I want to see how closely ...
20 views

### Analysing pre and post intervention MCQ results for significance- which statistical test to use?

I have ran a teaching course for students. I carried out pre and post session MCQ quizzes to evidence effectiveness of the course, however the marks collected were anonymised (data collected via ...
126 views

### Calculation of standard deviation of the mean changes from the p-value or z-value of the Wilcoxon test

I am conducting a meta-analysis of observational studies without a control group that compared a parameter's value before and after an operation. All included studies have reported their results as ...
307 views

### Scale of measurements in sign test and signed rank test

Can some one help me to understand the right scale of measurement to use in sign test as well as in signed rank test? I read a certain book it says nominal scale is used in sign test while ordinal ...
74 views

### What exactly does the “symmetric distribution” assumption of the Wilcoxon signed-rank test refer to? [duplicate]

I have two lists (or sets) of data that I would like to statistically compare. More precisely, I would like to check if the difference between data list one and data list two is statistically ...
15 views

### Determining KAP assessment post-intervention significance: use a paired t-test, signed-rank Wilcoxon, or other?

I'm newer to statistics and unsure how to analyze my data for a cohort study (n=73) where KAP assessments were administered to the same pregnant women before and after an educational intervention for ...
62 views

### Do I always have to consider all possible pairs in post-hoc pairwise comparison?

I performed an ANOVA on some test results of N groups (N = 7), which yielded a significant difference of the group means, followed by a wilcoxon signed-rank test to determine which groups are ...
92 views

### Wilcoxon sign rank test in R does not match with GraphPad Prism

I am comparing several combinations of two columns of non-normally distributed paired data: I used R with the following syntax: wilcox.test(x, y, paired=T) I tried to replicate this test in GraphPad ...
46 views

### Study results showed that the posttest scores got lower than the pretest scores, yet wilcoxon results show that there is significant difference

We had a study on the effectiveness of a learning intervention. We collected pre and post test scores and the results showed us that the students' scores got lower in posttest than the pretest. But ...
7k views

### Wilcoxon Signed Rank Symmetry Assumption

The assumption of symmetricity for signed rank test (and its relevance) is becoming extremely confusing for me. I am hypothesizing that sub-population A (before treatment) and sub-population B (after ...
1 vote
31 views

### Is the Wilcoxon Signed Rank Test appropriate when the Brier score is the accuracy metric?

When comparing model performance, is it valid to use the Wilcoxon signed rank test for matched pairs, when the accuracy metric is the Brier score? (Here, the Brier score is used in calculating the OOB ...
46 views

### Assessing the Impact of a Specific Treatment on Survey Results: A Wilcoxon Signed-Rank Test Approach on Paired Samples

I have conducted a survey with several scale questions ranked 1-10 on a sample of n=18. I applied a specific treatment before and after the survey. However, I'm unsure about how to analyze the data ...
6k views

### What method is preferred, a bootstrapping test or a nonparametric rank-based test?

I want to perform a single-tail test on a single sample of real numbers (N~100) against an expected value. The population is known to be not normally distributed. So from what I've read about stats, I ...
51 views

### How to run Wilcoxon signed-rank test for pairwise comparison of two factors with three variables each?

I performed a study where I took 9 measurements from each participant for 2 factors (time/ location) and 3 variables each. These created the following combinations: T1L1, T1L2, T1L3, T2L1, T2L2, T2L3, ...
93 views

### Wilcoxon Rank Test Pre/Post By gender

I am trying to compare the paired pre to post-responses in a student survey to see if gender plays a role. I was told to do a wilcoxon signed ranked test, and I can get the mean and p-value by each ...
1 vote
14 views

### How to analyse ordinal data for five food samples

I've conducted a questionnaire asking participants to rate biscuit samples based on factors such as taste and look. The ratings ranged from strongly like to strongly dislike. What is the best method ...
1 vote
192 views

### Paired sign and Wilcoxon tests with weighting

In R, I am using the survey package (inverse probability weighting) to conduct these tests on paired data: Weighted Wilcoxon Signed Rank test Weighted Sign test However, I am struggling in doing ...
48 views

### Test on significant difference

I need to test if there is a significant difference in leakage between prototypes. I've tried kruskal wallis and post hoc wilcoxon pairwise and Dunn-Bonferroni test, and the post hoc test always say ...
105 views

### Why is the pseudomedian better than the median in a Wilcoxon test?

The wilcox.test function in R calculates the pseudomedian and a confidence interval when conf.int=TRUE. In this question, ...
4k views

### How to best visualize one-sample test?

We are currently writing a paper with several one-sample Wilcoxon tests. While visualizing two-sample tests is easy via boxplots, I was wondering whether there is any good way to visualize one-sample ...
5k views

### Relative efficiency of Wilcoxon signed rank in small samples

I have seen in published literature (and posted on here) that the asymptotic relative efficiency of the Wilcoxon signed rank test is at least 0.864 when compared to the t test. I have also heard that ...
582 views

### Is Wilcoxon Test appropriate for paired categorical data?

There is currently a story in the news in the UK about negative effects of puberty blockers in children: 'It showed that after a year on puberty blockers, there was a significant increase found in ...